1. Field of the Invention
The present invention relates to a vehicular lamp having a projection lens that condenses light irradiated from the light source and more particularly to a vehicular lamp further provided with a second light source.
2. Description of the Related Art
Lamps known as projector-type lamps have recently been used as front lamps (headlamps) and auxiliary lamps (fog lamps) for automobiles. Such projector-type lamps generally include a projection lens that is formed by a condenser lens and is provided in front of the light source; and in such projector-type lamps, light irradiated from the light source is reflected by a reflector and condensed at a rear-side focal point of the projection lens or a nearby position thereof, so that the condensed light is projected by the projection lens. This type of projector-type lamps provide a wide illumination range while enabling downsizing of the light irradiation surface on the front surface of the lamp, and thus they are advantageous in terms of achieving lamps of a smaller size.
In addition, some projector-type lamps use a semiconductor light-emitting element, such as a light-emitting diode (LED), as the light source; and such projector-type lamps that use LEDs have been proposed greatly in recent years since such lamps further contribute downsizing of the reflector and projection lens as disclosed in, for example, United States Patent Application Publication No. 2006/0104077.
In such a projector-type lamp as described above, in order to obtain a targeted light distribution pattern (illumination pattern), a shade for blocking light is internally disposed so that it is located between the reflector and the projection lens. A part of light flux reflected by the reflector and incident to the projection lens is, as a result, blocked so that the light flux irradiated from the projection lens is limited.
The lamp disclosed in, for example, Japanese Patent Application Laid-Open (Kokai) No. 01-67804 is provided with a shade which is formed such that an upper edge portion thereof follows horizontal and oblique cut-off lines in order to provide a low-beam light distribution pattern for an automobile. Furthermore, the lamp proposed in the above-described publication has a configuration that a second light source is provided inside the lamp body, so that the second light source can be selectively lit in order to increase the variety of obtainable light distribution patterns and achieve light illumination that adapts to various running conditions of the automobile.
The lamp of the above-described publication uses incandescent bulbs for its light source (which is a first light source) and second light source. However, two incandescent bulbs inside the lamp results in an extremely large amount of heat when both incandescent bulbs are lit at the same time, thus resulting in an issue of heat release. Particularly problematic matters are significant temperature increases in the shade provided to face the first light source and of the projection lens provided to face the second light source. As a result, use of a semiconductor light-emitting element such as an LED for the second light source is a conceivable solution. For example, by using an LED as the second light source, at least the temperature increase in the opposing projection lens can be suppressed.
However, in the lamp of the above-described publication (Japanese Patent Application Laid-Open (Kokai) No. 01-67804), since the second light source is provided between the projection lens and the front side of the shade, the second light source is exposed through the projection lens and consequently worsens the overall outer appearance of the lamp. Also, since no shade to control the light flux with respect to the second light source is provided, it is difficult to secure a space for providing a shade. This in turn makes it difficult to provide a desired light distribution pattern when the second light source is lit.